2 Samuel 7:4-5, 12-14, 16; Psalm 88:2-5, 27, 29; Romans 4:13,16-18,22; Matthew 1:16, 18-21,24
There is so little known about St Joseph - other than a few verses in the Gospels. However what is known is so significant: we can trace his ancestry back through King David (our first reading), and then back to Abraham (as the letter to the Romans says - 'I have made you the ancestor of many nations'.)
Joseph, then, links Jesus firmly back into the covenants made between God and mankind in the Hebrew Scriptures. The prophet Nathan tells King David that his line will endure, and we are told Joseph has the pivotal role of bringing the infant Jesus - not his natural born son - into the line of David by persevering in his betrothal to Mary and thus adopting the infant.
Jesus coming from the line of David was one of several key signs that He is the messiah.